Combined telephone and electrothermostatic fire-alarm system.



'No. 647,588. Patented Apr. l7, i900. a. K. THOMPSON. COMBINED TELEPHONE AND ELECTROTHERMOSTATIC FIRE ALARM SYSTEM.

(Application filed Aug. 5, 1899.) (No-Modal.) 2 Sheats.$henf Subscribed? Station 0:2.

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No. 647,588. Patented Apr. 17,1900.

0.. K. THOMPSON. CDHBENED TELEPHONE AND ELEGTRUTHERMUSTATIC FIRE ALARM SYSTEM.

Y (Application filed Aug. 5, 1899.) (No Model.) 2 Sheets-Sheet 2.

Inventor,

Pn'rnr GEORGE K. THOMPSON, OF MALDEN, MASSACHUSETTS, ASSIGNOR TO THE AMERICAN BELL TELEPHONE OOh'lPANY, OF BOSTON, MASSACHUSETTS.

COMBINED TELEPHONE AND ELECTROTHERMOSTATIC FIRE-ALARM SYSTEM.

SPECIFICATION forming part of Letters Patent N 0. 647,588,

dated April 17, 1 900.

Application filed August 5, 1899- Serial No: 726,231. (No model.)

To ctZZ 1071,0121 it may concern:

Be it known that I, GEORGE K. THOMPSON, of Malden, in the State of Massachusetts, have invented a new and useful Improvement in 5 CombinedTelephoneandElectrothermostatic Fire-Alarm Systems, of which the following is a specification.

Many electrothermostatic systems for giving an alarm of fire automatically at a dis- Io tance more or less remote from the immediate locality of the fire have been devised, and means have been devised for electrically connecting a local fire-alarm thermostat with a subscribers circuit in a telephone-exchange,

I5 whereby heat causing a thermostat to open or close an electric circuit will cause a signal to be conveyed over a telephone'circuit to the central office of the telephone-exchange. Such devices and means, however, have ineluded and required much additional electrical mechanism at both the subscribers station and the centralstation and in most cases, it not all, have included and required additional signaling devices and even additional local batteries or similar additional sources of eleetromotive force. The present invention employs no additional source of electromotive force either at a subscribers station or at the central station, no mechanism or apparatus of any sort in addition to the mechanism and apparatus in ordinary use at present at the central station in many telephoneexchanges, and only a very limited amount of electromechanism at a subscribers station in addition to the telephone outfit in ordinary use thereat and a suitable electrothermostat.

The invention consists in the combination, with a subscribers outfit at a subscribers station in a common-battery telephone-exchange, the line connecting said subscribers station with the central station of said exchange, the common source of electromotive force, and electromechanism at said central station adapted for ordinary use in connection with said subscribers outfit, of an electrothermostat at said subscribers station in a branch parallel or in multiple with the branches containing the severalinstruments of said subscribers outfit, a continuouslyacting circuit-modifier, and a magnetic device adapted to bc energized by the operation of said electrothermostat in closing the branch in which said electrothermostat islocated, and thereby bring into circuit with said common source of electromotiveforce said continuously-acting circuit-modifier.

The invention consists also in details of construction, more especially in means for continuing the action of the circuit-modifier at the subscribers station if by chance the circuit is opened in the thermostat after having been once closed to give an alarm.

The invention consists, further, in a modification which may be employed at the subscribers station whereby the subscriber may cut out the fire-alarm apparatus While holding telephonic communication with the central office.

In the drawing" Figure lis adiagram representing two subscribers lines belonging to a common-battery telephone-exchange, with their substation outfits and so much of the apparatus at the central station as is used in connecting and disconnecting the said two lines for conversation, one of the said subscribers substations being furnished with fire-alarm apparatus according to the present invention. Fig. 2 is a diagram representing a modification of the fire-alarm electromechanism employed at the subscribers station in connection with the electrothermostat. Fig.

3 is a diagram representing more especially a device whereby the fire-alarm apparatus at the subscribers station may be cut out while conversation is carried on by the central office with subscriber. There is also shown a local-alarm device at the subscribers station. Fig. 4 represents a detail of construction, being substantially the same as Fig. 3 and for the same mechanical device device.

Since a striking feature of the invention consists in the fact that the common-battery telephone exchange upon which the firealarm system is engrafted continues to be operated as a telephone system in the same manner in which it has hitherto been operated in the absence of the fire-alarm system, it is of some importance to describe herein rather fully the construction and mode of operation of such common-battery telephon c-exchangc.

in the place of an electric purpose, but employing a 90 As before stated, such a system is represented at Fig. 1, where, as indicated, are shown the central station and two subscribers stations No. 1 and No. 2. bubscribers station No. 1 is connected with the central station by linewires w and 10 and is there represented in the usual manner by multiple spring-jacks, of which two, j andj are shown. There is also shown at the central station in Fig. 1 as belonging particularly to the connectingwires 10 10 of subscriber No. 1 a cut-off relay R, the winding of 'whose magnet is grounded at g and connects, as shown, with the testrings 1" and r of the spring-jacks] and j respectively. So, too, is shown the line-relay R adapted to operate a call-signal V, which in this instance is an incandescent lamp grounded at as shown.

The subscribers outfit at station No. 1 contains, as is usual in common battery telephone systems, the microphone M, handtelephone T, polarized bell E, induction-coil 1L, and telephone-switch s, the latter adapted to complete both the primary and secondary circuits through the said ind notion-coil when the telephone is off the hook or to open the same when the telephone is on the hook, as indicated. 0' is a condenser in the primary circuit of the induction-coil 7), its office being to break the circuit of the normal batterycurrent through the bell. Similar letters with even numbers indicate like instruments at subscribers station at No. 2, which is connected with the central station by wires 10 to at spring-jacks 3". So likewise test-rings r r, cut-off and line relays R R and call signal V to be used in connection with subscribers station No. 2 correspond to like instruments already described.

At the central station B is the common battery or the source of electromotive force common to all the subscribers circuits and also common .to all the circuits of the operators cords. Of these cords but one pair is shown, although each operator has several pairs. One pole of the battery 13 is grounded at 9 and everysubscribers circuit has at the central station a wire 10 leading from the opposite or live pole of the battery through the winding of the magnet of the line-relay R to a contact-plate e of the cut-off relay.

R, which contact-plate normally makes contact with wire w leading to subscribers station No. 1. Another contact-plate e normally makes contact with wire w, also leading to subscribers station No. 1 and grounded at 9 as shown. When the subscriber takes his hand-telephone T from the hook, a circuit is made from the ground g of the common battery B through wire 10 andthe winding of the magnet of line-relay R contact-plate e Wl18lU the secondary of induction-coil i, microphone M, wire w, and contact-plate e to ground 9 and the current established therein energizes the magnet of linerelay R and shunts current, as indicated, to operate the call-signal V.

One cord of each pair of the operators cords is called the answering-cord. It contains three wires 10*, w, and 10 insulated each from the others and connecting with a separate part of the answering plug P. Thus 10 connects with the tip of the plug designed to make contact with the lower spring of springjacks 7" 9' &c., while its other end passing through one winding 1 of a repeating-coil G makes electrical connection with the grounded pole of the battery 13'. Wire w connects with an insulated ring on plug P, which is designed to make contact with the upper spring of spring-jacks j 3' 650., while the other end of the said wire passing through the winding of the magnet ot the disconnecting-relay R and also through winding 3 0t repeating-coil G makes electrical connection with the live pole of battery B. The third wire 10 makes contact at one end with the sleeve of the plug P, through which it is designed to make electrical connection with the test-rings 4" 7 &c., of the spring-jacks j j, &c., while its other end passes through the disconnectingsignal V in this instance an incandescent lamp, and makes electrical connection with the live side of the battery, a branch from said wire 10 being provided with a contact, as shown, to shunt current from the said disconnecting-signal. Going now to the other or answering cord of the pair we have wires w 10 and w, of which wire 10 leads from the grounded side of the common source of electromotive force B, through winding 2 of the repeating-coil G, and through the ringing-key K and wire 10 to the tip of the plug P, which is designed to make contact with the lower spring of the spring-jacks 7' 7' &c. Wire w leads from the live side of the battery B, through the winding 4 of repeating-coil G, the winding of the magnet of disconnecting-relay B, through the ringing-key K, and wire w to the ring on plug P which is designed to make contact with the upper spring of the spring-jacks j j, &c. Wire w leads from the live side of the battery B through the disconnecting-signal V to the sleeve of the calling-plug P designed to make contact with the rings 0' r, &c., of the spring-jacks 1 .7

of which use-is made at the central station in the ordinary process of connecting two subscribers for conversation and disconnect ing them after conversation it is not necessary to say more than that E is the ringinggenerator, whose two poles are brought into connection with wires 10 and wire 10 by key K and so through the circuit 10 Q0 of subscribers line No. 2 with the bell and condenser at station 2, and that M is the opera tors microphone, .always in circuit, while H is the operators head-telephone brought into circuitby key K It is hardly necessary to point out that when plug P is inserted in a spring-jack 7' For further description of the apparatus belonging to line of subscriber No. 1 cut-oft relay R operates to break subscribers linewire circuits at contact-plates e and c and the two wires w and 10 become connected up with the windings 1 and 3 of the repeating-coil G. Similarly when plug P is inserted in a spring-jack of the line of subscriber No. 2 the two wires to and to become connected up with windings 2 and 4 f the repeating-coil G. Thus the insertion of the two plugs in the proper springjacks creates a talking-circuit when bot-h of the subscribers receiving-telephones are removed from their respective hooks.

It remains to describe the fire-alarm apparatus of the subscribers stations and its mode of operation in connection with the apparatus of the central station, whose normal operation in the telephone system has been minutely described in order that it may manifest that it is not disturbed by the provisions made for the operation therewith of the thermostatic fire-alarm system.

Confining the description to Fig. 1, except where otherwise especially mentioned, A is the electrothermostat. Any form of thermostat adapted to close an electric circuit at a required temperature would answer the purpose of this invention; but the form of thermostat shown in the drawings is a cable thermostat, preferred because it is readily placed anywhere and everywhere in the subscribers station, the same consisting of two copper wires a a insulated from each other, and a third wiref ofreadily-fnsible material wound with a and a and adapted to close a circuit between a and a by fusing at any required temperature.

A is an electromagnet belonging to the fire-alarm system. The upper winding of its two cores or the winding where but one is used, as shown in Fig. 2, is connected up at its two ends in or with wire a", which maybe regarded as a prolongation of wire a of the thermostat, and connects with one of the wires 20 of the subscribers telephone-circuit.

A is the circuit-modifier, the form shown at Fig. 1 being the well-known buzzer, consisting, essentially, of an electromagnet 0 and vibratory armature a The pivot of the armature N is connected with the pivot of the armature n by a wire (0 which includes the winding of electromagnet o. The armature 01 makes contact with a contact-point in a wire a, branching from wire (H, which may be regarded as a prolongation of the thermostat-wire a, and is connected up at all times with wire 20 of the subscribers circuit. A wire a containing a resistance (7, as shown, also connects wire a with the pivot of the armature N.

\Vhen the wires a and a of thermostatA, Fig. 1, are electrically connected, a fire-alarm circuit is established as follows: beginning with the ground g of the common batteryB, through the battery, wire 10, magnet-winding of linerelay R", con tact-plate 6 wire 20 wire a upper winding of electromagnet A thermostatic wires a? a, wire a wire 20, and con tact-plate e to ground at 9 The current of the circuit thus established energizes the magnet of the line-relay R and operates the line-signal V. The current also energizes electromagnet A whereby the armature N is so attracted as to close a contact with branch wire a, thereby establishing a shuntcircuit from wire 10 at subscribers station through wire a branch wire a, lower winding of electro magnet A armature N, wire a, winding of electromagnet 0, armature n branch wire a, wire a and wire w at subscribers station. This, as will readily be traced at Fig. 1, operates the buzzer A and the operator at the central station on responding to the call-signal given at V will hear in operators head-telephone the noise of the buzzer, indicating a fire at subscribers station No. 1.

It will be observed that when the shuntcircuit just described is established by the armature N making contact with the contactpoint of branch wire a if such shunt-circuit is maintained it is immaterial whether or not thereafter the circuit remains closed in the electrothermostat. In fact, the electrothermostat may itself be destroyed without causing the fire-alarm call or signal, once given, to cease. It is obvious that the shunt-circuit can be maintained in many ways-for i11- stance, let the contact-point with which N makes contact be furnished with alatch which will receive and hold the armature when the latter is attracted by its magnet. Such a device is shown at L, Fig. 4. At Fig. l'an electrical device is shown for maintaining the shunt, consisting of wire a furnished with a suitable resistance, connecting wire a with wire a A continuous circuit is thus maintained through the magnet of the line-relay R at the central office, and the ca1l-signal at V is also maintained notwithstanding the breaks in the operation of the buzzer or circuit-breaker at the subscribers station until the operator at the central station responds by inserting the plug P in one of the jacks j of the subscribers circuit, when on operating the listening-key K the clicks or noise due to the makes and breaks in the buzzer or circuit-modifier A at the subscribers station will be heard in the head-telephone H. The current at all times flowing through the wire a including its resistance d, is sufiicient to energize the magnet of the line relay R whether the circuit through the buzzer is closed or open.

In Fig. 2 the second winding of the magnet A is omitted, and the armature N, under the attraction of the said magnet, makes contact with a contact-point at the end of wire a leading directly from wire a. In this instance there is no provision for maintaining the circuit if it is broken in the electrothcrmostat after the alarm-signal has once been sentin. Within the invention, broadly con- :4 was" Fig. 1. cuits.

sidered, it is not necessary to make special provision for this maintenance of the circuit, as a contact of sufficient duration is expected to be madein the thermostat; but at the same time it is well to make such special provision, and accordingly the armature N in Fig. 2 may be provided with the latch mechanism shown at L, Fig t. At Fig. 2, also, a circuitbreaker A, operated by clock mechanism, as indicated, takes the place of the buzzer of It is unnecessary to trace the cirthe armature N is attracted byits magnet A The wire a and resistance (1 in Fig. 2 serve the same purpose as in Fig. 1 in regard to the maintenance of a steady current through the line-relay B In Fig. 3, besides the apparatus at the subscribers station already described, the switch operated by taking the hand-telephone from the hook for the purpose of establishing'the telephone-circuit is made to do the further duty of cutting out the fire-alarm apparatus at the subscribers station. Two spring-contacts t and t in wires a and a respectively, both normally closed, are opened by two nonconducting plugs Z and 1 when the telephone at subscribers station is taken from the hook, as indicated. This permits conversation to be carried on between subscriber and operator after a fire alarm has once been given without the annoyance of noise in the circuitbreaker. cialalarm-signal A at the subscribers station. This is an ordinary vibrating bell grounded at g and brought into circuit with the common battery at the central station by the movement of the armature N, as indicated.

It is unnecessary to trace the circuit.

I have thus far shown and described the line connecting the subscribers station with the central station as a metallic circuit-line, andI have shown for the apparatus employed at the central station that which is employed in common-battery exchanges where the subscribers lines are either all metallic or part metallic and part grounded; but it is obvious that the invention is equally applicable to common-battery telephone-exchan ges in which the subscribers lines may'all be grounded. I So,

too, the only circuit-modifying instruments shown and described as operating to be heard in the central operators head-telephone when the electrothermostat-circuit is closed at the subscribers station have been well -known forms of circuit-breakers; but it is obvious that other circuit-varying instruments may be substituted therefor if so arranged as to'be energized by the common battery or common source of electromotive forceat the central station. Again,'it would be within a substantial part of the invention to omit the branch line a and resistance 01 of Fig. 1 and depend upon the character of the visual signal at V to determine whether a regular call is sent in from station 1 (a steady light) or a fire-alarm call, (a flash or wavering light.)

The clock mechanism is released when- There is also shown at Fig. 3 a spe-- I claim-- 1. In a common battery telephone exchange, the combination with a subscribers outfit at asubscribers station, the lineleading therefrom to the central station, the common source of electromotive force, and the electromechanism at said central station adapted to be used in connection with said subscribers outfit, of an electrothermostat at said subscribers station,in abranch parallel or in multiple with the branches containing the instruments of said subscribers outfit, a continuously-acting circuit-modifier, and an electromagnet device adapted to be energized by the operation of said electrothermostat in closing the branch in which said electrothermostat is located and thereby bring into circuit with said common source of electromotive force said con tinuously acting circuit=modifier,sub-

stantially as described.

2. In a common; battery telephone-etichange, the combination with a subscribers outfit at the station including said outfit and a common source of electromotive force, of an electrothermostat in a branch parallel or in multiple with the branches containing the instruments of said outfit, -a continuously-act- 'ing circuit-modifier, and an electromagnetic device adapted to be energized. by the operation of said electrothermostat in closing the said branch in which said electrothermostat is located, and thereby bring into the common circuit of the exchange over subscribers line,

said continuously acting circuit modifier,

substantially as described.

3. In a common -bat-tery telephone exchange, the combination with a subscribers line, the outfit at the subscribers station and a common source of electromotive force, of an electrothermostat in a branch parallel with the branches containing the instruments of said subscribers out fit and adapted when operated by heat to close a circuit over the subscribers line and set up therein a current from the source of electromotive force of the exchange, an electromagnet so arrangedthat the said current established by the operation of the thermostat passes through its winding, a conductor leading from the branch in which the thermostat is connected, in advance of the magnet, an armature for said electromagnet adapted when attracted by said electromagnet to make electrical connection with said conductor, and a circuit-modifier in electrical connection with said armature adapted with said armature and said conductor to short-circuitsaidthermostat, substantially as described.

4. In a common battery telephone exchange, the combination with a subscribers line, the outfit at the subscribers station and a common source of electromotive force, of an electrothermostat in a branch parallel with the branches containing the instruments of said subscribers outfit and adapted when operated by heat to close a circuit over the said subscribers line and set up therein a current from the source of electromotive force of the exchange, a double-wound electromagnet so arranged that the said current established by the operation of the thermostat passes through one winding thereof, an armature for said electromagnet adapted when attracted by said electromagnet to make permanent electrical connection with the second Winding thereof, and a circuit-modifier in electrical connection with said armature, and adapted with said armature and said second winding to permanently short-circuit said thermostat, substantially as described.

5. In a common battery telephone eX- change, the combination with a subscribers outfit at a subscribers station, the line leading therefrom to the central station, the common source of electromotive force, and the electromechanism at said central station adapted to be used in connection with said subscribers station, of an electrothermostat, in a branch parallel with the branches containing the instruments of said subscribers outfit, adapted when operated by heat to close a circuit over said subscribers line and set up therein a current from said common source of electromotive force,a continuously-aotin g circuit-modifier, an electromagnet so arranged that the said current established by the operation of said thermostat will pass through its winding, magnet in electrical connection with said continuously-acting circuit-modifier and so arranged that, when attracted by said electromagnet, it will make electrical connection with said winding and thereby bring into circuit with said common source of electronictive force said continuously-acting circuitmodifier, substantially as described.

GEORGE K. THOMPSON.

\Vitnesses:

WINFIELD S. HUToHINsoN, WILLIAM S. NIXON.

and an armature for said electro- 

